Method for forming insulating film, apparatus for processing substrate, and system for processing substrate

ABSTRACT

There is provided a technique of forming an insulating film containing silicon oxide. A coating solution containing polysilazane is applied onto a wafer W, the solvent of the coating solution is volatilized, and the coating film is irradiated with ultraviolet rays in nitrogen atmosphere before performing a curing process. Dangling bonds are generated in silicon which is a pre-hydrolyzed site in polysilazane. Therefore, the energy for hydrolysis is reduced, and unhydrolyzed sites are reduced even when the temperature of the curing process is 350° C. Since efficient dehydration condensation occurs, the crosslinking rate is improved, and a dense (good-quality) insulation film is formed. By forming a protective film on the surface of the coating film to which ultraviolet rays irradiated, the reaction of dangling bonds prior to the curing process is suppressed.

This is a Divisional Application of U.S. patent application Ser. No.16/645,712, filed Mar. 9, 2020, an application filed as a national stageunder 371 of Application No. PCT/JP2018/031810 filed Aug. 28, 2018 andclaiming benefit from Japanese Application No. 2017-174287, filed Sep.11, 2017, the content of each of which is hereby incorporated byreference in its entirety.

TECHNICAL FIELD

The present disclosure relates to a technology of forming an insulatingfilm that is a silicon oxide-containing coated film and is hardened by across-linking reaction.

BACKGROUND

There is a process of forming an insulating film such as a silicon oxidefilm in the processes of manufacturing semiconductor devices. Theinsulating film is formed, for example, by plasma CVD or by applying acoating liquid. An insulating film formed by plasma CVD has an advantagethat a high quality film is obtained because it is dense, butembeddability is poor. Accordingly, for example, the insulating film isnot suitable when an insulator is embedded in a fine groove called aShallow Trench Isolation (STI). Accordingly, for example, it is requiredto gradually embed the insulating film such that a gap is not generated,by repeating plasma CVD and etch-back, so the process of forming a filmis complicated or a large-scale apparatus is required to perform vacuumprocessing.

Further, according to a method of forming an insulating film by applyinga coating liquid to a semiconductor wafer (hereafter, referred to as a‘wafer’) through spin coating, etc., and then curing the coated film,embeddability is good, so it is easy to fill even fine patterns such asan STI with an insulating film. Further, there is an advantage thatprocessing can be performed in an ordinary pressure atmosphere, butthere is problem that the strength of the film is relatively low.Accordingly, the strength of the film is increased, for example, byperforming a heat treatment (curing) on a coated film at 600 to 800degrees C.

However, according to a miniaturization of the pattern, there is arequest for suppressing a thermal history for a semiconductor device tobe manufactured as low as possible. Therefore, for example, when aninterlayer insulating film is formed, the temperature cannot beincreased over 400 degrees C. in light of migration of copper (Cu)wires, diffusion of Cu, etc. Therefore, the method of forming aninsulating film by applying a coating liquid cannot be applied to aninterlayer insulating film due to the high curing temperature.

A technology of forming an insulating film by forming a coated film,heating the coated film at a low temperature, and then processing thecoated film at a high temperature in a water vapor atmosphere isdescribed in Patent Document 1, but it does not solve the problemssolved by the technology of the present disclosure.

PRIOR ART DOCUMENTS Patent Documents

-   Patent Document 1: Japanese Laid-Open Patent Publication No.    2012-174717.

SUMMARY

The purpose of the present disclosure is to provide a technology thatachieves a good quality of a film when forming an insulating filmcontaining a silicon oxide as a coated film on a substrate.

According to one embodiment of the present disclosure, there is provideda method for a method of forming an insulating film, the methodincluding: a process of forming a coated film on a substrate by applyinga coating liquid, which is obtained by dissolving a precursor forforming an insulating film containing silicon oxide in a solvent, to thesubstrate; a solution volatilization process of volatilizing the solventin the coated film; subsequently, an energy supply process of supplyingenergy to the coated film in a low-oxygen atmosphere having aconcentration of oxygen lower than an atmospheric atmosphere to formdangling bonds at molecular groups constituting the precursor; a processof forming, on a surface of the coated film, a protective film forsuppressing oxidation of the dangling bonds in the coated film due tothe atmospheric atmosphere; and subsequently, a curing process offorming the insulating film by heating the substrate and crosslinkingthe precursor.

According to another embodiment of the present disclosure, there isprovided an apparatus for processing a substrate, including: a coatingmodule configured to form a coated film on a substrate by applying acoating liquid, which is obtained by dissolving a precursor for formingan insulating film containing silicon oxide in a solvent, to thesubstrate; a solvent volatilization module configured to volatilize thesolvent in the coated film; an energy supply module configured to supplyenergy to the coated film in which the solvent has been volatilized, ina low-oxygen atmosphere having a concentration of oxygen lower than anatmospheric atmosphere so as to activate the precursor; a protectivefilm formation module configured to form a protective film on the coatedfilm to which the energy has been supplied; and a substrate transfermechanism configured to transfer the substrate between the respectivemodules.

According to yet another embodiment of the present disclosure, there isprovided a system for processing a substrate, including: an apparatusfor processing a substrate which includes: a load/unload port configuredto load/unload the substrate accommodated in a transfer container; acoating module configured to form a coated film on the substrate byapplying a coating liquid, which is obtained by dissolving a precursorfor forming an insulating film containing silicon oxide in a solvent, tothe substrate; a solvent volatilization module configured to volatilizethe solvent in the coated film; an energy supply module configured tosupply energy to the coated film in which the solvent has beenvolatilized, in a low-oxygen atmosphere having a concentration of oxygenlower than an atmospheric atmosphere so as to activate the precursor; aprotective film formation module configured to form a protective film onthe coated film to which the energy has been supplied; and a substratetransfer mechanism configured to transfer the substrate between therespective modules and the load/unload port; a heat treatment apparatusconfigured to form the insulating film by heating the substrateprocessed in the apparatus for processing the substrate and crosslinkingthe precursor; and a container transfer mechanism configured to transferthe transfer container between the load/unload port of the apparatus forprocessing the substrate and the curing apparatus.

According to the present disclosure, a coating liquid containing aprecursor of an insulating film containing a silicon oxide is applied toa substrate, a solvent in the coating liquid is volatilized, and energyis supplied to the coated film in a low-oxygen atmosphere before acuring process is performed. Accordingly, dangling bonds are easilyproduced at portions that are hydrolyzed in the precursor. In the curingprocess, hydroxyl groups are bonded to silicon at molecular groupsconstituting the precursor by hydrolysis at first, and then crosslinkingis performed by dehydration condensation of the hydroxyl groups at themolecular groups. However, by forming dangling bonds in advance atsilicon that is the portions that are hydrolyzed, production efficiencyof the hydroxyl groups is increased. That is, since the energy forhydrolysis decreases, the portions remaining without hydrolyzingdecreases even if the curing process is performed at a low temperature.As a result, dehydration condensation efficiently occurs, so acrosslinking rate is improved and it is possible to form a dense(good-quality) insulating film.

Further, it is possible to suppress reaction of dangling bonds beforethe curing process by forming a protective film on the surface of acoated film after supplying energy to the coated film, whereby thequality of the coated film is improved.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram illustrating a general curing process for aninsulating film.

FIG. 2 is a diagram illustrating a curing process for an insulating filmof the present disclosure.

FIG. 3 is a diagram illustrating a process of forming an insulating filmaccording to an embodiment of the present disclosure.

FIG. 4 is a diagram illustrating a process of forming an insulating filmaccording to an embodiment of the present disclosure.

FIG. 5 is a diagram illustrating a process of forming an insulating filmaccording to an embodiment of the present disclosure.

FIG. 6 is a diagram illustrating a process of forming an insulating filmaccording to an embodiment of the present disclosure.

FIG. 7 is a diagram illustrating a process of forming an insulating filmaccording to an embodiment of the present disclosure.

FIG. 8 is a diagram illustrating a reaction path of polysilazane in ageneral film-forming processing.

FIG. 9 is a diagram illustrating a reaction path of polysilazane in afilm-forming processing of the present disclosure.

FIG. 10 is a diagram illustrating a planarization of a surface of aninsulating film.

FIG. 11 is a plan view showing a system for processing a substrateaccording to an embodiment of the present disclosure.

FIG. 12 is a plan view showing an apparatus for processing a substrate.

FIG. 13 is a vertical cross-sectional view of the apparatus forprocessing a substrate.

FIG. 14 is a cross-sectional view showing a coating module disposed inthe apparatus for processing a substrate.

FIG. 15 is a cross-sectional view showing a solution volatilizationmodule disposed in the apparatus for processing a substrate.

FIG. 16 is a cross-sectional view showing an ultraviolet radiationmodule disposed in the apparatus for processing a substrate.

FIG. 17 is a cross-sectional view showing a vertical heat treatmentapparatus disposed in a heat treatment apparatus.

FIG. 18 is a diagram illustrating a process of forming an insulatingfilm according to a second embodiment.

FIG. 19 is a cross-sectional view of a wafer according to the secondembodiment.

FIG. 20 is a diagram illustrating a process of forming an insulatingfilm according to the second embodiment.

FIG. 21 is a diagram illustrating a process of forming an insulatingfilm according to another example of an embodiment of the presentdisclosure.

FIG. 22 is a diagram illustrating a process of forming an insulatingfilm according to another example of an embodiment of the presentdisclosure.

FIG. 23 is a diagram illustrating a process of forming an insulatingfilm according to another example of an embodiment of the presentdisclosure.

FIG. 24 is a diagram illustrating a process of forming an insulatingfilm according to another example of an embodiment of the presentdisclosure.

FIG. 25 is a diagram illustrating a process of forming an insulatingfilm according to another example of an embodiment of the presentdisclosure.

FIG. 26 is a diagram illustrating a process of forming an insulatingfilm according to another example of an embodiment of the presentdisclosure.

FIG. 27 is a characteristic diagram showing a relative etching rate inExample 3.

DETAILED DESCRIPTION

[Summary of Disclosure]

The contents of the present disclosure are described before embodimentsof the present disclosure are described. As an example of a method offorming an insulating film of the present disclosure, there may be aprocess of applying a coating liquid containing a precursor of aninsulating film containing a silicon oxide to a substrate, volatilizinga solvent in the obtained coated film by heating the coated film,subsequently, rearranging the molecular groups in the coated film byheating the substrate, after that, radiating ultraviolet rays to thecoated film, and then curing the coated film.

The coating liquid is produced by dissolving groups of oligomer that aremolecular groups of the precursor of the insulating film containing asilicon oxide into a solution that is a solvent. In a general curingprocess, Si—OH is produced by hydrolysis (reaction) between H₂O (water)and Si—H bonds of oligomer, as shown in FIG. 1 , by heating a substrateat 500 degrees C., for example. Further, dehydration condensation(reaction) occurs, whereby Si—O—Si bonds are produced and oligomers arecross-linked.

The reason that oligomer is used as a component of the coating liquid isbecause when all of precursor is connected, it is not solved in asolution. For these reasons, the state of oligomer, that is, the stateof the precursor before the hydrolysis described above is stable and thehydrolysis is a process that changes the stable state into an unstablestate, so it is difficult to promote hydrolysis. Accordingly, it isrequired to increase the temperature for curing or induce reaction for along time at a low temperature.

Meanwhile, the dehydration condensation (reaction) quickly progressesjust by giving thermal energy. For these reasons, when the temperaturefor curing is increased to promote hydrolysis, dehydration condensation(in which Si—OH becomes Si—O—Si) easily occurs rather than hydrolysis(in which Si—H becomes Si—OH), so denseness of an insulating film islow. It is generally presumed that the reason is because when someoligomers are cross-linked by dehydration condensation, other oligomershave not been hydrolyzed yet and are introduced into the crosslinkingsubstances of the some oligomers. Further, according to the method ofperforming curing for long time at a low temperature, the throughput islow, so the method is difficult to be used in a production line.

Accordingly, in the present disclosure, for example, ultraviolet raysare radiated to a coated film before a curing process is performed sothat dangling bonds are produced (oligomers are so-called activated) atparts where hydrolysis occurs. That is, as shown in FIG. 2 , danglingbonds are produced by cutting Si—H bonds in oligomer using the energy ofthe ultraviolet rays. For these reasons, the energy necessary forhydrolysis in the curing process decreases, so the production efficiencyof hydroxyl groups (OH-groups) increases and a crosslinking rate by thefollowing dehydration condensation is improved. This means that a denseinsulating film (having a good film quality) is obtained even if acuring process is performed at a low temperature.

It is required to radiate the ultraviolet rays to the coated film beforeperforming the curing process. The reason is that even though the curingprocess is performed at a low temperature, it is performed in a heatingatmosphere of, for example, 350 to 450 degrees C. For these reasons,when dangling bonds are produced by the energy of the ultraviolet rays,as described above, crosslinking occurs from the portion where danglingbonds have been generated, and thus, oligomers in which Si—H bonds havenot yet been cut are locked in cross-linked oligomer groups. Therefore,denseness of an insulating film decreases.

Accordingly, it is necessary to perform the process of radiating theultraviolet rays to the coated film at a temperature at which thisphenomenon is suppressed. Specifically, for example, a temperature under350 degrees C. is considered as being preferable. For example, theprocess may be performed at a room temperature. Further, the process ofradiating the ultraviolet rays to the coated film needs to be performedin a low-oxygen concentration atmosphere having an oxygen concentrationlower than an atmospheric atmosphere. Thus, the process is performed,for example, in an atmosphere with oxygen concentration of 400 ppm orless, preferably, 50 ppm or less. The low-oxygen concentrationatmosphere may be, for example, an inert gas atmosphere such as nitrogengas.

When the oxygen concentration is high in the atmosphere in which theprocess is performed, oligomers having dangling bonds produced byradiated the ultraviolet rays instantaneously bond to each other, andisolated oligomers are locked in the bonded oligomers, which results indecreased denseness of an insulating film.

After the process of radiating the ultraviolet rays to the coated film,for example, while the substrate is transferred from the substrateprocessing apparatus that has radiated the ultraviolet rays to thesubstrate to a heat treatment furnace for a curing treatment, thesubstrate may stand for a period (be left for a period) in aroom-temperature atmospheric atmosphere in a state in which, forexample, the substrate is stored in a receiving container. When danglingbonds are produced on the surface of the coated film by radiating theultraviolet rays to the coated film, since the reactivity of the coatedfilm is high, the dangling bonds are easily oxidized by oxygen or waterin the atmosphere. However, when dangling bonds are oxidized at a lowtemperature, for example, in a range of room temperature, an oxide filmhaving a low strength is formed, and thus the quality of the film isdeteriorated. Accordingly, in the present disclosure, a protective filmfor suppressing an oxidation of a coated film is formed on the surfaceof the coated film before the substrate is taken out of the apparatusfor processing a substrate. As the protective film, as described below,for example, an organic film, such as a dense oxide film, may be used.

First Embodiment

Next, an embodiment of a method of forming an insulating film of thepresent disclosure is described in detail. As a method of forming aninsulating film using the system for processing a substrate, a processof performing STI on a target substrate is described. As shown in FIG. 3, grooves 110 (trenches) are formed in a silicon film 100 of a wafer Wthat is a target substrate. A coating liquid obtained, for example, bydissolving a precursor of SOG film in an organic solution is applied tothe wafer W, whereby a coated film 101 is formed to fill the trenches110. For example, polysilazane that is a polymer having —(SiH₂)NH— as afundamental structure is used as the precursor. In the coating liquid,for example, molecular groups of polysilazane are dissolved in anoligomer state to improve fluidity. Accordingly, as shown in FIG. 3 ,when a coating liquid is applied to the wafer W, for example, by spincoating, the coating liquid easily enters the narrow trenches 110, sothat the coated film 101 having a good embedding ability is obtained.Further, the coated film 101 is indicated as PSZ (polysilazane) in FIGS.3 to 10 .

Next, as shown in FIG. 4 , the wafer W is heated at 100 to 250 degreesC., for example, 150 degrees C., for 3 minutes. Accordingly, the solventcontained in the coated film 101 volatilizes. Thereafter, as shown inFIG. 5 , energy of 5000 mJ/cm² or less, for example, 4000 mJ/cm² isapplied to the coated film 101 in an oxygen concentration atmosphere of400 ppm, preferably, 50 ppm or less, for example, in a nitrogen (N₂) gasatmosphere. As the energy, for example, ultraviolet rays (UV) having amain wavelength of 200 nm or less, for example, the ultraviolet rayshaving a main wavelength of 172 nm is radiated. The main wavelength is awavelength corresponding to the maximum peak or a periphery thereof in aspectrum.

Next, an organic film 102 that is, for example, a protective film ofpolystyrene is formed on the surface of the coated film 101.Accordingly, as shown in FIG. 6 , the surface of the coated film 101 iscovered with the organic film 102, so that it is possible to suppress acontact between dangling bonds produced in the coated film 101 and theatmospheric atmosphere. Further, since the organic film 102 ishydrophobic, it is possible to prevent water in the atmosphere frompermeating into the coated film 101.

Since the dangling bonds formed on the surface of the coated film 101have high reactivity, they easily react with oxygen or water in theatmospheric atmosphere. If the dangling bonds are oxidized in a range ofa room temperature, the reaction smoothly progresses, so an oxide filmwith low denseness may be formed on the surface of the coated film 101.Accordingly, by covering the surface of the coated film 101 with theorganic film 102, it is possible to suppress a contact between thedangling bonds formed on the surface of the coated film 101 and theatmospheric atmosphere, and it is possible to suppress the formation ofan oxide film having a low denseness on the surface of the coated film101.

Further, in a next curing process, as shown in FIG. 7 , heating isperformed in stages at 350 to 450 degrees C. For example, under a watervapor atmosphere, heating is performed at 400 degrees C. and thenperformed at 450 degrees C. and heating is performed at 450 degrees C.in a N₂ gas atmosphere while water vapor is supplied to the wafer W. Inthis process, since the organic film 102 formed on the coated film 101is polystyrene, it sublimates into water and carbon dioxide and iseasily removed by heating, so the surface of the coated film 101 isexposed. The coated film 101 is heated at a temperature of 350 to 450degrees C. in a water vapor atmosphere.

FIG. 8 shows a reaction path when the curing treatment was performed onpolysilazane without radiating the ultraviolet rays. FIG. 9 shows areaction path when the curing treatment was performed on polysilazane towhich the ultraviolet rays have been radiated. As shown in FIG. 8 , whenthe curing treatment is applied to polysilazane, H bonding to Si becomesan OH-group by hydrolysis, an N—H-group oxides into ammonia (NH₃), andSi—O bonds are produced. Further, OH-groups form crosslinks throughdehydration condensation. However, as described above, since thehydrolysis is difficult to occur when the curing treatment is performed,a film having a low denseness is formed.

However, by radiating the ultraviolet rays to the coated film 101containing polysilazane before the curing treatment, as shown in FIG. 9, in addition to Si—H bonds are cut to form dangling bonds, and someSi—N bonds are cut to form dangling bonds. Accordingly, when the curingtreatment is performed, an OH-group easily bonds to the dangling bond toform Si—OH. Further, the OH-groups form crosslinks through dehydrationcondensation to form a Si—O—Si bond. Further, the Si—N bonds ofpolysilazane are substituted by O to form a silicon oxide. As describedabove, since dangling bonds are formed in advance and the productionefficiency of OH-groups is high and a crosslinking rate is improved, aninsulating film (silicon oxide film) having a good quality is formed.

After the insulating film is hardened, as shown in FIG. 10 , theremaining coated film 101 on the surface of the wafer W is removed, forexample, by Chemical Mechanical Polishing (CMP). When the strength ofthe coated film 101 is low, it is difficult to polish the coated film101 by CMP. However, the coated film 101 is the silicon oxide filmhaving a high denseness, so the strength of the coated film 101 issufficiently high. Accordingly, the coated film 101 is polished by CMP,and the silicon film 100 is exposed on the surface of the wafer W.

Next, the system for processing a substrate that forms an insulatingfilm is described. As shown in FIG. 11 , the system for processing asubstrate includes a substrate processing apparatus 1 for processing asubstrate such as a coating treatment that applies an insulating film ona wafer W, and a heat treatment apparatus 93 including a heat treatmentfurnace that performs heat treatment on the wafer W, for example, avertical heat treatment apparatus 97. A transfer vehicle (AVG) 98 thatis a container transfer mechanism for transferring a carrier C betweenthe substrate processing apparatus 1 and the heat treatment apparatus 93is provided. Between the substrate processing apparatus 1 and the heattreatment apparatus 93, a loading table 90 is provided on which thewafer W accommodated in the carrier C is loaded and stands for a periodbefore the wafer W is transferred to the heat treatment apparatus 93after processing is finished in the substrate processing apparatus 1.

As shown in FIGS. 12 and 13 , in the substrate processing apparatus 1, acarrier block S1, a relay block S2, and a processing block S3 areconnected in a line. The carrier block S1 is a load/unload port forloading and unloading the wafers W from the carrier C, which is atransfer container accommodating a plurality of wafers W, to theapparatus.

The carrier block S1 has a stage 11 on which a plurality of (e.g.,three) carriers C for accommodating and conveying a plurality of wafersW is loaded, for example, in a lateral direction (in the direction X) asshown in FIG. 12 . Further, the carrier block S1 has a conveyancemechanism 12 that is a transfer arm for conveying the wafers W into thecarriers C loaded on the stage 11. The conveyance mechanism 12 isconfigured such that a portion in which the wafers W are held andsupported is capable of moving forward/backward, moving in the directionX, rotating about a vertical axis, and moving up/down.

The relay block S2 has a function of conveying the wafers W taken out ofthe carriers C in the carrier block S1 to the processing block S3. Therelay block S2 has a conveyance shelf 13 on which a plurality of loadingtables of the wafers W are vertically disposed, and a transfer mechanism14 capable of moving up/down to transfer the wafers W between theloading tables of the conveyance shelf 13. On the conveyance shelf 13,the loading tables for the wafers W are disposed at height positionswhere main transfer mechanisms 15 a and 15 b provided in the processingblock S3 can convey the wafers W and a conveyance mechanism 42 canconvey the wafers W.

The processing block S3, as shown in FIG. 13 , has a two-layeredstructure in which processing blocks B1 and B2 are stacked up and down.The processing blocks B1 and B2 have substantially similarconfigurations, so the processing block B1 shown in FIG. 12 isexemplified. The processing block B1 has the main conveying mechanism 15a capable of moving along a transfer path 16, which may be a guide railextending in a front-rear direction (direction Y) when seen from therelay block S2. Modules for performing processing on wafers W aredisposed at left and right sides of the transfer path 16 in theprocessing block B1. In the processing block B1, a coating module 2 forapplying an insulating film and an organic film is disposed at the rightside when seen from the carrier block S1. Further, at the left side, forexample, three solution volatilization modules 3 and two ultravioletradiation modules 5 are disposed in parallel from the relay block S2side.

Further, a controller 91 such as a computer is disposed in the apparatusfor forming an insulating film. The controller 91 has a program storage.The program storage stores programs having instructions for executing asequence of transferring the wafers W in the apparatus or processing thewafers W in the modules. The programs are stored in a storage mediumsuch as a flexible disc, a compact disc, a hard disk, a Magneto-Optical(MO) disc, and a memory card, and are installed in the controller 91.

Next, the coating module 2 is described. The coating module 2, forexample, performs coating on the wafer W in which a pattern is formed,using well-known spin coating. The coating module 2 includes aninsulating film coating module 2A that applies a coating liquid obtainedby dissolving polysilazane, which is a precursor of an insulating film,in an organic solution, and an organic film coating module 2B which is amodule for forming an organic film that applies an organic film on thesurface of the wafer W to which the ultraviolet rays have been radiated.Among the insulating film coating module 2A and the organic film coatingmodule 2B, the insulating film coating module 2A applies polysilazane onwafers W. Further, the organic film coating module 2B has a similarconfiguration except for, for example, applying polystyrene, so theinsulating film coating module 2A is exemplified herein.

The insulating film coating module 2A, as shown in FIG. 14 , has a spinchuck 21 which sucks and holds a wafer W and is capable of being rotatedand moved up/down by a driving mechanism 22. Further, reference numeral23 in FIG. 14 indicates a cup module. Reference numeral 24 in FIG. 14indicates a guide member having a circular plate shape and having anouter circumferential wall extending downward from the circumferentialedge.

A discharge space is formed between an external cup 25 and the outercircumferential wall. A lower portion of the discharge space has astructure capable of separating gas and liquid. A liquid receiving part27 is disposed around the guide member 24 to extend toward a centralportion from an upper end of the external cup 25, and receives theliquid centrifugally separated from the wafer W. The insulating filmcoating module 2A has a coating liquid nozzle 28. The insulating filmcoating module 2A forms a coated film by supplying a coating liquid to acenter portion of the wafer W through the coating liquid nozzle 28 froma coating liquid supply source 29 storing a coating liquid such aspolysilazane while rotating the wafer W about a vertical axis with apredetermined number of revolutions, which allows to spread the coatingliquid on the surface of the wafer W. Similarly, the organic filmcoating module 2B forms an organic film by supplying polystyrene to thewafer W through the coating liquid nozzle 28 while rotating the wafer Wabout a vertical axis with a predetermined number of revolutions, whichallows to spread the coating liquid on the surface of the wafer W.

Next, the solution volatilization module 3 that volatilizes a solutionwhich is a solvent is described. As shown in FIG. 15 , the solutionvolatilization module 3 includes a processing container 30 composed of alower part 31 constituted by a flat cylindrical body having an open topsurface in a housing not shown, and a cover 32 disposed opposite thelower part 31. The cover 32 is configured to move up/down by an elevator37 disposed on an upper surface of a bottom surface 3 a of the housing.The processing container 30 is opened by moving up the cover 32. Thelower part 31 is supported through a supporting member 41 on the bottomsurface 3 a of the housing. In the lower part 31, there is provided aheating plate 33 having a heater 34 buried therein for heating the waferW mounted on the lower part 31, for example, at 100 to 250 degrees C. Onthe bottom surface 3 a of the housing, there is provided an elevator 36for moving up/down elevation pins 35, which penetrate through a bottomof the lower part 31 and the heating plate 33 to convey the wafer Wbetween the processing container 30 and the main conveying mechanism 15a disposed outside the processing container 30.

The cover 32 is a flat cylindrical body having an open bottom surface.An exhaust hole 38 is formed at a center portion of the top plate of thecover 32. An exhaust pipe 39 is connected to the exhaust hole 38. When aside of the processing container 30 is defined as an upstream of theexhaust pipe 39, a downstream of the exhaust pipe 39 is connected to acommon exhaust duct laid in a factory.

The cover 32 is mounted on the lower part 31 to form a processing spacein which the wafer W is heated, while the cover 32 is in contact with apin 40 disposed on an upper surface of a peripheral wall of the lowerpart 31 and forms a slight gap between the cover 32 and the lower part31. When a gas is evacuated from the exhaust hole 38, an atmosphere inthe housing is introduced into the processing container 30 from the gapbetween the cover 32 and the lower part 31. The cover 32 is configuredto be capable of moving up/down between a lowered position where theprocessing container 30 is closed by the cover 32 and a raised positionwhere a wafer W is conveyed to the heating plate 33.

As shown in FIG. 16 , the ultraviolet radiation module 5, which is anenergy supply module, includes a housing 50 having a rectangularparallelepiped shape that is flat and is narrow and long in a front-reardirection. A load/unload port 51 for loading/unloading the wafers W anda shutter 52 for opening/closing the load/unload port 51 are disposed ona side wall surface of the housing 50 in a front side.

A transfer arm 53 that transfers the wafer W is disposed at a frontportion in the housing 50 when seen from the load/unload port 51. Thetransfer arm 53 is a cooling plate, and is configured to cool the waferW to a room temperature (25 degrees C.), for example, before theultraviolet rays are radiated after a solution volatilization process. Aloading table 54 for the wafer W is disposed inside when seen from theload/unload port 51. Elevation pins 56 and 58 for conveying the wafersare disposed under the loading table 54 and the transfer arm 53,respectively. The elevation pins 56 and 58 are configured to moveup/down by elevators 57 and 59, respectively.

A ramp chamber 70 accommodating an ultraviolet lamp 71 for radiating theultraviolet rays to the wafer W loaded on the loading table 54, such asa xenon excimer lamp radiating the ultraviolet rays having a mainwavelength of 172 nm, is disposed at a side. A light transmission window72, for example, made of quartz and transmitting ultraviolet lighthaving a wavelength of 172 nm and radiated from the ultraviolet lamp 71to the wafer W is disposed in a bottom surface of the lamp chamber 70.Further, a gas supply part 73 and an exhaust port 74 are disposed toface each other in a side wall of a lower portion of the lamp chamber70. A N₂ gas supply source 75 for supplying N₂ gas into the housing 50is connected to the gas supply part 73. An exhaust mechanism 77 isconnected to the exhaust port 74 through an exhaust pipe 76.

Further, when the ultraviolet rays are radiated to the wafer W loaded onthe loading table 54, N₂ gas is supplied from the gas supply part 73while evacuating the housing 50, so that the atmosphere around the waferW, for example, becomes a low-oxygen atmosphere of 400 ppm or less, forexample, a N₂ gas atmosphere. When the wafer W cooled up a roomtemperature is loaded on the loading table 54 by the transfer arm 53, ina state in which N₂ gas is supplied from the N₂ gas supply source 75 toform the low-oxygen atmosphere, an energy of, for example, 2000 mJ/cm²is radiated to the wafer W.

The flow of a wafer W in the apparatus for forming an insulating film isbriefly described. When the carrier C accommodating the wafer W isloaded on the stage 11, the wafer W is transferred to the processingblock B1 or B2 via the conveyance mechanism 12, the conveyance shelf 13,and the transfer mechanism 14. Thereafter, the coated film 101 isapplied to the wafer W in the insulating film coating module 2A and thenthe wafer W is transferred to in order of the solution volatilizationmodule 3, the ultraviolet radiation module 5, and the organic filmcoating module 2B, whereby the insulating film is formed. Thereafter,the wafer W is conveyed to the conveyance shelf 13 and then is returnedto the carrier C by the transfer mechanism 14 and the conveyancemechanism 12.

Next, the heat treatment apparatus 93 is described. The heat treatmentapparatus 93, as shown in FIG. 11 , includes a carrier block S1 intowhich a carrier C is transferred, a conveyance mechanism 94 taking thewafer out of the carrier C, a loading shelf 96 on which the wafers W areloaded, and a transfer mechanism 95 transferring the wafers W loaded onthe loading shelf 96 into a heat treatment furnace.

For example, as shown in FIG. 17 , a vertical heat treatment apparatus97 may be used as the heat treatment furnace. The vertical heattreatment apparatus 97 includes an inner reaction tube 103 and acylindrical outer reaction tube 104. The inner reaction tube 103 is areaction tube having a tube shape made of quartz, having both open ends,and being supplied with a film-forming gas. The cylindrical outerreaction tube 104 is made of quartz, has a closed upper end and an openlower end, and is disposed around the inner reaction tube 103. Amanifold 115 having a tubular shape is disposed under the outer reactiontube 104. The manifold 115 is made of stainless steel, and ishermetically connected to an opening of the outer reaction tube 104 tobe extended from the outer reaction tube 104. A flange 117 is formed atthe lower end of the manifold 115. A ring-shaped supporting portion 116is formed inside the manifold 115. The lower end of the inner reactiontube 103 is vertically connected to an inner circumferential portions ofthe supporting portion 116. The inner reaction tube 103, the outerreaction tube 104, and the manifold 115 correspond to a reactioncontainer 111.

The vertical heat treatment apparatus 97 further includes an insulator113 covering the outer reaction tube 104 from its upper side. The lowerportion of the insulator 113 is fixed to a base 109 fixing the reactioncontainer 111. A heater 114, which is a resistance heating body, isdisposed around the entire circumference inside the insulator 113.

A circular cover 119 made of quartz and opening/closing an opening 118surrounded by the flange 117 of the manifold 115 is disposed over theopening 118. The cover 119 is installed on a boat elevator 120 thatmoves up/down the cover 119. A rotary table 121 is disposed on the uppersurface of the cover 119, and is configured to be capable of rotatingabout a vertical axis by a driver 122 disposed under the boat elevator120.

An insulating unit 123 is disposed above the rotary table 121. A waferboat 105 that is a substrate holder is disposed over the insulating unit123. The wafer boat 105 has a ceiling plate 124 a and a bottom plate 124b. In a support 125 connecting the ceiling plate 124 a and the bottomplate 124 b, holding grooves 126 for holding the wafers W in a shelfshape inserted therein is formed.

A water vapor supply nozzle 127 and a N₂ gas supply nozzle 128 that is apurge gas supply part are disposed under the supporting portion 116 ofthe manifold 115. The water vapor supply nozzle 127 horizontally extendsand has a front end that is open as a gas supply hole. A base end of thewater vapor supply nozzle 127 is connected to a port 115 a formed at themanifold 115. One end of a water vapor supply pipe 131 is connected tothe port 115 a from the outer circumference of the manifold 115. Theother end of the water vapor supply pipe 131 is connected to a watervapor supply source 132 through a valve V131 and a flow regulator M131.

Further, the N₂ gas supply nozzle 128 has a horizontal portion and avertical portion extending in an arrangement direction of the wafers W.A base end of the N₂ gas supply nozzle 128 is connected to a port 115 bformed at the manifold 115. Further, an end of N₂ gas supply pipe 133 isconnected to the port 115 b from the outer circumference of the manifold115. The other end of the N₂ gas supply pipe 133 is connected to a N₂gas supply source 134 through a valve V133 and a flow regulator M133.

One end of an exhaust pipe 136 having the other end connected to avacuum exhaust mechanism 135 is connected to a portion of the manifold115 above the supporting portion 116 to discharge gas from a portioninside the manifold 115 above the supporting portion 116, that is, fromthe gap between the outer reaction tube 104 and the inner reaction tube103.

According to the vertical heat treatment apparatus 97, for example, thewafer W, which is accommodated in the carrier C and loaded in the heattreatment apparatus, is accommodated in the wafer boat 105 while thecover 119 is moved down. Further, when the cover 119 is moved up, asshown in FIG. 17 , the wafer boat 105 is stored into the reactioncontainer 111, and the opening 118 is closed by the cover 119. Further,water vapor is supplied into the reaction container 111 from the watervapor supply nozzle 127, while the wafer W is heated to a predeterminedtemperature, for example, 450 degrees C. by the heater 114, whereby thecuring treatment is performed on the wafer W.

Further, the heat treatment apparatus 93, as shown in FIG. 11 , alsoincludes a controller 92 for performing, for example, the transfer ofthe wafer W in the heat treatment apparatus 93 or the curing treatmenton the wafer W in the vertical heat treatment apparatus 97. Thecontroller 92 has a program storage. The program storage stores programshaving instructions for executing a sequence of conveying the wafers Win heat treatment apparatus 93 or processing the wafers W in thevertical heat treatment apparatus 97. The programs are stored in astorage medium such as a flexible disc, a compact disc, a hard disk, aMagneto-Optical (MO) disc, and a memory card, and are installed in thecontroller 92. Further, the system for processing a substrate includes ahigher rank computer 99 for performing the method of forming theinsulating film described above by transmitting/receiving control signalto/from the controller 91 of the substrate processing apparatus 1 andthe controller 92 of the heat treatment apparatus 93 and by controllingconveyance of the carrier C by the transfer vehicle 98.

Further, the wafer W in which the processing has been finished in thesubstrate processing apparatus 1, is stored in the carrier C and thenconveyed to the loading table 90 by the transfer vehicle 98. Further,for example, until processing by the heat treatment apparatus 93 isstarted, the wafer W is left for a period on the loading table 90, forexample, for one day. Thereafter, when the turn of processing by theheat treatment apparatus 93 is reached, the carrier C is conveyed to thecarrier block S1 of the heat treatment apparatus 93 by the transfervehicle 98, and the curing process described above is performed.

According to the embodiment described above, the coating liquidcontaining polysilazane is applied to a wafer W, the solution in thecoated film 101 is volatilized, and then the ultraviolet rays areradiated to the coated film 101 in a nitrogen atmosphere before thecuring process is performed. Accordingly, dangling bonds are easilyproduced at a part that is hydrolyzed in polysilazane. Since danglingbonds are produced in advance in silicon that is the part to behydrolyzed, the production efficiency of a hydroxyl group increases.That is, since energy for hydrolysis decreases, the part remainingwithout being hydrolyzed decreases, even when the temperature of thecuring process is 350 degrees C. As a result, dehydration condensationefficiently occurs, and a crosslinking rate is improved, so that it ispossible to form a dense insulating film (having a good quality).

Further, an organic film 102 is formed on the surface of the coated film101 before a substrate is transferred from the substrate processingapparatus 1. Accordingly, even though a wafer W accommodated in thecarrier C and taken out of the substrate processing apparatus 1 is leftfor a period on the loading table 90, it is possible to suppress theformation of an oxide film having a low denseness caused by slowoxidation of dangling bonds. Accordingly, the coated film 101, which isformed on the wafer W after the curing process, is dense and thedifferences in quality of films between the wafers W can be suppressed.

The organic film may be removed before the curing treatment is appliedto the coated film. For example, a liquid processing apparatus thatsupplies rinse to the wafer W may be provided in the heat treatmentapparatus 93. After dissolving and removing the organic film byperforming rinsing treatment on the wafer W using the liquid processingapparatus, the wafer W may be transferred to the vertical heat treatmentapparatus 97. A liquid processing apparatus that supplies rinse to thesubstrate processing apparatus 1 may be provided. Before transferringthe wafer W to the heat treatment apparatus 93, the wafer W may betransferred from the loading table 90 to the substrate processingapparatus 1 to perform a rinsing treatment, and then the wafer W may bequickly transferred the wafer to the heat treatment apparatus 93.

After performing the curing treatment on the wafer W, an ashingtreatment may be performed by heating the wafer W. The organic film 102may be dissolved and removed by performing heating in the ashingtreatment. Acryl may be used for the organic film 102. Alternatively, aresist may be used.

In the process of volatilizing a solution shown in FIG. 4 , a reflowprocess that rearranging oligomers in the coated film 101 may beperformed. For example, during forming SOG film, gaps are generatedbetween the oligomers contained in the coated film in some cases when acoated film is formed and then a solution is removed. For these reasons,after performing the process of removing the solution, the wafer W maybe heated at 200 to 300 degrees C., for example, at 250 degrees C.Accordingly, the oligomers in the coated film 101 are rearranged to fillgaps (the reflow process). Since the oligomers are rearranged by thereflow process, the gaps between the oligomers become narrow.Accordingly, a dense film is easily obtained when crosslinks ofoligomers are formed by the curing treatment to be performed.

As such an apparatus, in the substrate processing apparatus 1 shown inFIG. 12 , one of the solution volatilization modules 3 may be set as aheating module (reflow module) capable of heating a wafer W, forexample, at 200 to 300 degrees C. for example, 250 degrees C.

Further, in the embodiment described above, the curing treatment may beperformed by heating the wafer while supplying ammonia gas in the curingprocess. Alternatively, N₂ gas may be supplied in the curing treatment.

Further, the present disclosure may be applied to forming an interlayerinsulating film such as a low dielectric film. When forming aninterlayer insulating film, it is required to maintain a heatingtemperature, for example, at 400 degrees C. or less in order to suppressmigration or diffusion of copper that is a wire material. Since ahigh-quality insulating film is obtained even if the curing temperatureis low in the present disclosure, the present disclosure can be appliedto forming an interlayer insulating film.

Further, for example, the present disclosure may be applied to Pre MetalDielectric (PMD) as an example of forming an insulating film on asubstrate with narrow grooves.

Second Embodiment

Next, a method of forming an insulating film according to a secondembodiment of the present disclosure is described. In this embodiment,after the process of radiating the ultraviolet rays to the coated film101 shown in FIG. 5 , the ultraviolet rays are further radiated to thecoated film. For example, the ultraviolet rays of a dosage of 2000mJ/cm² are radiated when the ultraviolet rays are primarily radiated tothe coated film, and then the ultraviolet rays of a dosage of 1000mJ/cm² are radiated as a process of secondarily radiating theultraviolet rays to the coated film.

The amount of energy that is supplied to the coated film and activity ofthe coated film are described. As shown in the schematic diagram of FIG.18 , when energy is radiated to a coated film, energy exceeding apredetermined tolerance E1 is given to form dangling bonds. However,when energy exceeding a tolerance E2 is further given, activity of thecoated film excessively increases, whereby the activity increases suchthat the coated film easily reacts with oxygen or water in theatmosphere at a room temperature. Further, by performing the followingcuring treatment in a state in which energy exceeding the tolerance E1is given to the entire layer of the coated film, the entire layer of thecoated film becomes a dense oxide film.

In this case, when the ultraviolet rays are radiated to the coated film,as shown in FIG. 18 , activity increases on the surface of the coatedfilm, the energy is gradually attenuated as the energy permeates fromthe surface of the coated film. Accordingly, by radiating theultraviolet rays to make the entire layer of the coated film receive theenergy Ea of is E1<Ea<E2, having a dosage, for example, a dosage of 2000mJ/cm², the distribution of energy that is applied in the depthdirection of the coated film, for example, becomes that shown in (1) ofFIG. 18 . Further, the ultraviolet rays of a dosage of 1000 mJ areradiated when the ultraviolet rays are secondarily radiated, whereby, asshown in (2) of FIG. 18 , a layer receiving energy exceeding thetolerant E2 is formed in an upper layer having a very small thickness d.Further, the lower layer may be a layer that receives energy between thetolerance E1 and the tolerance E2. In this case, since the tolerance E1is exceeded in the entire layer of the coated film, dangling bonds areformed in the layer, and in the region with the thickness d of thesurface layer, activity has increased such that the coated film easilyreacts with oxygen or water of the atmosphere at a room temperature.

Further, when the wafer W is exposed to the atmosphere, as shown in FIG.19 , rapid oxidation occurs due to oxygen or water in the atmosphere inthe layer to which energy exceeding the tolerance E2 of the surface hasbeen supplied. Since oxidation reaction rapidly progresses, an oxidefilm 106 having very high denseness is formed even though it isoxidation in the atmospheric atmosphere. In this case, since activityhas not been increased such that oxidation rapidly occurs in the layerunder the layer to which energy exceeding the tolerance E2 has beensupplied, bonding of dangling bonds does not progresses, so the danglingbonds are maintained in the layer. The dense oxide film 106 correspondsto a protective film. Further, the inventors found out that when theultraviolet rays over 3000 m/cm² were radiated to the wafer W. and thewafer W has been left for one day, an oxide film is formed on thesurface layer of a coated film of the wafer W, and oxidation does notprogress in the coated film. Further, it was found that the entire layerbecame an oxide film by the curing treatment performed later. Further,as described in a following third embodiment, since an oxide film havinghigh resistance against etching was formed, it is estimated that a denseoxide film was formed.

When a dense film is formed on the surface of a coated film, oxygen orwater in the atmosphere is difficult to permeate into the coated film.Accordingly, when the wafer W is maintained in an atmospheric atmosphereat a room temperature, the layer in which dangling bonds are formedunder the dense film does not come in contact with oxygen or water inthe atmosphere, so the layer is protected in a state in which theactivity is maintained. Thereafter, in a curing process, since rapidoxidation progresses due to heating and a water vapor atmosphere, thewater vapor passes through the dense layer on the surface layer of thecoated film, thereby promoting oxidation of dangling bonds disposedunder the dense layer. Water vapor permeates into the coated film, asdescribed above, whereby a dense oxide film is formed. According to thisconfiguration, a protective film is formed on the surface of the coatedfilm, slow oxidation of the protective film of the coated film in anatmospheric atmosphere at a room temperature can be suppressed, so thesame effect can be obtained.

Further, it may be possible to form a dense oxide film in the surface ofthe coated film by forming a layer to which energy exceeding thetolerance E2 has been radiated in the surface of the coated film bysecondarily radiating the ultraviolet rays, and then exposing the coatedfilm in an atmospheric atmosphere, as in the embodiment described above.Alternatively, it may be possible to forcibly form a dense oxide film byforming a layer to which energy exceeding the tolerance E2 has beenradiated in the surface of the coated film and then supplying oxygen tothe surface of the coated film.

Further, the ultraviolet rays that are secondarily radiated may be theultraviolet rays having a shorter wavelength than that of theultraviolet rays primarily radiated. As described above, when theultraviolet rays are radiated to a coated film, the ultraviolet rayspermeate into a deep position from the surface, so the energy isgradually attenuated. In this case, the attenuation speed of energy inthe depth direction of the coated film increases when the wavelength λaof the ultraviolet rays is long, as shown in the graph in (3) of FIG. 20, than that when the wavelength λb of the ultraviolet rays is short, asshown in (4) of FIG. 20 (λa>λb). Accordingly, when a layer in which theactivity exceeding a tolerance E2 is formed in the surface of the coatedfilm by radiating the same dosage of the ultraviolet rays, the thicknessof the layer to which energy exceeding the tolerance E2 is radiated isda when the wavelength of the ultraviolet rays is long. On the otherhand, when the wavelength of the ultraviolet rays is small, thethickness of the layer to which energy exceeding the tolerance E2 isradiated is db smaller than da. Accordingly, when the wavelength of theultraviolet rays is small, a thinner dense oxide film is formed whenoxidation occurs due to contact with the atmosphere, as compared withthe wavelength is large.

A layer oxidized in the atmospheric atmosphere by applying energy overthe tolerance E2 in advance becomes dense, but it is not a filmgenerally formed by the curing treatment, so there is a possibility thatthe property may be different from a Si—O—Si bond formed by the curingtreatment. Accordingly, it is possible to form a thin oxide film that isa protective film by making the layer to which energy exceeding thetolerance E2 is radiated thin by radiating the ultraviolet rays having asmall wavelength to a coated film, so the uniformity of the quality ofthe film becomes good when the entire layer is oxidized by performingthe curing treatment.

In the embodiment described above, the ultraviolet rays are radiatedtwice to the coated film. However, the illuminance of the ultravioletrays may be increased to radiate the ultraviolet rays once as much asthe sum of the dosages of the ultraviolet rays radiated twice in theembodiment, for example, of a dosage of the ultraviolet rays of a dosageof 3000 mJ/cm². Even in this case, the very thin layer in the surface ofthe coated film reaches a dosage of energy exceeding an allowable level,and a state in which a dosage of energy of the allowable level isreached can be formed in the coated film. Accordingly, since it ispossible to form a dense film in the very thin layer in the surfacelayer of the coated film, the same effect can be obtained.

Further, it may be possible to form a dense film in the surface of thecoated film by increasing the total time of radiating the ultravioletrays to the coated film. By increasing the radiation time of theultraviolet rays, the dosage of the ultraviolet rays that are radiatedto the coated film can be increased, so that the same effect isobtained.

In the second embodiment, if the dosage of energy that is radiated tothe coated film 101 is excessive, the denseness of the oxide film formedin the surface of the coated film 101 excessively increases.Accordingly, it is difficult for water vapor to permeate into the coatedfilm 101 in the curing process, so the coated film 101 may be difficultto oxidize. Accordingly, it is preferable that the radiation amount ofenergy is 5000 J/cm² or less.

After the ultraviolet rays are radiated to the coated film, before theprotective film is formed, the coated film may be exposed to a catalyticatmosphere such as ammonia gas. As an apparatus for this example, theapparatus may supply ammonia gas to the wafer W loaded on the loadingtable 54, for example, by further providing a gas supply part to theultraviolet radiation module 5 shown in FIG. 16 . After radiating theultraviolet rays, for example, of a dosage of 2000 mJ/cm² to the coatedfilm using the aforementioned ultraviolet radiation module 5 to formdangling bonds, the coated film is exposed, for example, for one minutein an ammonia gas atmosphere by supplying ammonia gas to the wafer W.Since the reactivity of the coated film has been increased by theradiated ultraviolet rays, ammonia easily permeates into the coatedfilm. Thereafter, the surface of the coated film is further activated byradiating the ultraviolet rays of a dosage of 1000 mJ/cm², and thecoated film is exposed to the atmospheric atmosphere, whereby a denseoxide layer may be formed in the surface of the coated film.

When the wafer W is conveyed into the heat treatment apparatus and thecuring treatment is performed, dangling bonds become Si—O—Si bonds dueto heating under a water vapor atmosphere. In this case, dehydrationcondensation progresses due to a catalytic effect of the ammoniapermeating in the coated film, and the reaction of the dangling bondsbecoming the Si—O—Si bonds is promoted. According to this configuration,since the Si—O—Si bonds can be more securely formed in the coated film,more dense oxide film can be obtained. Acid or alkali may be used as theatmosphere that is a catalyst. Further, a liquid-state catalyst such asTetra Methyl Hydroxide (TMH) may be used. When the liquid-state catalystis used, a stagnation of liquid may be formed on the surface of thewafer W by radiating the ultraviolet rays to the coated film to formdangling bonds and subsequently supplying TMH to the surface of thewafer W while rotating the wafer W about a vertical axis. Accordingly, acatalyst can permeate into the coated film. Further, since the activityof the surface of the coated film is increased by radiating theultraviolet rays to the coated film and the coated film is exposed tothe atmospheric atmosphere, an oxide film that is a protective film canbe formed on the surface of the coated film containing the catalyst.

As the apparatus for putting the catalyst into the coated film, acatalyst addition module that makes the atmosphere for the substrate bea catalyst atmosphere in the substrate processing apparatus 1 and addsthe catalyst to the coated film may be provided. Further, a plurality ofultraviolet radiation modules 5, for example, a first ultravioletradiation module 5 and a second ultraviolet radiation module 5 may beprovided. In this case, for example, after ultraviolet ray of a dosageof 2000 mJ/cm² is radiated using the first ultraviolet radiation moduleto a wafer W that has undergone a solution volatilization process, thewafer W is conveyed to the catalyst addition module, and a catalyst isadded to the coated film. Further, the wafer W may be transferred to thesecond ultraviolet radiation module 5 and the ultraviolet rays of adosage of 1000 mJ/cm² may be radiated to the coated film to increaseactivity of the surface of the coated film.

The present disclosure may form an insulating film by applying a coatingliquid several times. In this case, for example, the substrateprocessing apparatus 1 shown in FIGS. 12 and 13 may include a curingtreatment module that can supply water vapor to a wafer W and can heatthe wafer W, for example, to 450 degrees C. First, a wafer W havingtrenches 110 formed thereon is transferred to the insulating filmcoating module 2A and then a coating liquid is primarily applied.Accordingly, for example, as shown in FIG. 21 , a coated film 101 ahaving the coating liquid entered in a trench 110 formed on a siliconfilm 100 is formed. In FIGS. 21 to 26 , the coated film formed byprimarily applying the coating liquid is indicated by 101 a, and thecoated film formed by secondarily applying a coating liquid is indicatedby 101 b.

Thereafter, similar to an embodiment, after the wafer W is transferredto the solution volatilization module 3 to volatilize the solution, forexample, the wafer W is transferred to the ultraviolet radiation module5 to radiate the ultraviolet rays of a dosage of 2000 mJ/cm² to thecoated film 101 a in a low-oxygen atmosphere, as shown in FIG. 22 .Next, the wafer W is transferred to the curing treatment module toperform a curing process at 450 degrees C. for 120 minutes in a watervapor atmosphere, as shown in FIG. 23 . Thereafter, the wafer W istransferred to the insulating film coating module 2A to performsecondary coating. Accordingly, the coated film 101 b is further stackedon the wafer W, as shown in FIG. 24 . Thereafter, the wafer W istransferred to the solution volatilization module 3 to volatilize thesolution, and then the wafer W is transferred to the ultravioletradiation module 5 to radiate the ultraviolet rays of a dosage of 2000mJ/cm² to the coated film 101 b in a low-oxygen atmosphere, as shown inFIG. 25 . Next, the ultraviolet rays of, for example, a dosage of 1000mJ/cm² are further radiated to the coated film 101 b, thereby increasingthe activity of the surface of the coated film.

Thereafter, the wafer W is accommodated in the carrier C and taken outof the substrate processing apparatus 1, and then left for a period onthe loading table 90. Subsequently, the wafer W is transferred to theheat treatment apparatus 93. Further, as shown in FIG. 26 , for example,the wafer W is heated in stages at 400 degrees C. and 450 degrees C.under a water vapor atmosphere, and then heated at 450 degrees C. in aN₂ gas atmosphere.

When the ultraviolet rays are radiated to the coated films 101 a and 101b, since the ultraviolet rays permeate downward from the surface layersof the coated films 101 a and 101 b to the lower layers of the coatedfilms 101 a and 101 b, the ultraviolet rays easily weaken in the lowerlayers in comparison to the surface layers of the coated films 101 a and101 b, and there is a possibility that Si—H bonds do not sufficientlybecome dangling bonds. Accordingly, when the curing treatment is appliedto the wafer W, the crosslinking rate may be low in the lower layers ofthe coated films 101 a and 101 b, and the crosslinking rate of theentire film may decrease. Further, for example, when the coated film inthe surface layer is removed by CMP, a layer having low quality of thecoated film may be exposed.

For these reasons, the coated films 101 a and 101 b having predeterminedfilm thicknesses are formed by repeating, plural times, the applicationof the coated films 101 a and 101 b and the radiation of the ultravioletrays, thereby being able to radiate the ultraviolet rays in a state inwhich the coated films 101 a and 101 b are thin. Accordingly, danglingbonds are easily formed in the entire layers of the coated films 101 aand 101 b. Therefore, when the curing treatment is performed,crosslinking is easily formed in the entire layers of the coated films101 a and 101 b, and the crosslinking rate is high in the entire layers,such that dense coated films 101 a and 101 b can be formed. Further,when the wafer W is taken out of the substrate processing apparatus 1, adense oxide film 106 that is a protective film is formed on theuppermost coated film 101 b in an atmospheric atmosphere. Accordingly,the dangling bonds in the coated films 101 a and 101 b are protectedwithout being oxidized when the wafer W is left for a period.

Further, after the solution is volatilized through the primary coatingand the secondary coating, a reflow process that heats the wafer W, forexample, at 250 degrees C. may be performed.

Further, if temperature is increased up to temperature at whichcrosslinking progresses in the process of radiating the ultravioletrays, for example, if temperature is increased up to 350 to 400 degreesC. in polysilazane, formation of dangling bonds, hydrolysis, anddehydration condensation may simultaneously occur. Accordingly, isolatedoligomers are locked in bonded oligomers, and the denseness of theinsulating film decreases.

For these reasons, it is preferable that temperature at which theultraviolet rays are radiated is 350 degrees C. or less. Further, whenthe ultraviolet rays are radiated, since it is required to set thetemperature at which the crosslinking should not progress, theultraviolet rays may be radiated in the reflow process. However, in thesolution volatilization process, the solution may be deteriorated due tothe radiated ultraviolet rays. Accordingly, the radiation of theultraviolet rays needs to be performed after the solution removalprocess.

Further, as in Example 2 described below, it is possible to increase theeffect of the method of forming an insulating film described above bymaintaining the temperature for heating the wafer W at 200 to 250degrees C. in the solution volatilization process. This is estimated asan increasing effect obtained due to reduction of energy that isabsorbed in the solution by more securely removing the solution in thecoated film 101, and due to an effect corresponding to rearrangement ofoligomers generated by performing the reflow process even though thereflow process is not performed in Example 2.

Further, it is preferable energy has a wavelength that is absorbed inthe coated film without passing through the coated film in respect ofeffective formation of dangling bonds. Accordingly, it is preferablethat the main wavelength of the ultraviolet rays is 200 nm or less. Forexample, the ultraviolet rays having a wavelength of 193 nm such as anArF lamp may be used, and a heavy hydrogen lamp may be used. Electronrays may be used as the energy that is radiated to a coated film.

Further, the apparatus, which is used in the solution volatilizationprocess to volatilize the solution in the coated film 101, may be anapparatus that volatilizes a solution by reducing the internal pressureof an airtight processing container, for example, to a half of theatmospheric pressure to promote the volatilization of the solution inthe wafer W loaded in the processing container.

EXAMPLES

The following tests were performed to examine the effect of anembodiment of the present disclosure. An insulating film was formed on awafer W for a test using the system for processing a substrate shown inFIG. 11 , and the etching strength of the insulating film was estimated.

Example 1

An example defined as Example 1-1 was conducted by radiating ultravioletrays having a main wavelength of 172 nm in a N₂ gas atmosphere in theprocess of radiating the ultraviolet rays in the method of forming aninsulating film such that the dosage becomes 2000 mJ/cm². In Example1-1, the coating liquid described in the embodiment was applied to thewafer W, the wafer W is heated at 150 degrees C. for 3 minutes in thesolution volatilization process, and then the process of radiating theultraviolet rays was performed without performing the reflow process.Next, the wafer W was transferred to a heat treatment apparatus withoutbeing left for a period. Subsequently, in the curing process, the waferW was heated through two stages performed at 400 degrees C. for 30minutes and at 450 degrees C. for 120 minutes with water vapor suppliedin a heat treatment furnace, and then the wafer W was heated at 450degrees C. in a N₂ gas atmosphere. The target thickness of a coated filmwas 100 nm.

Comparative Examples 1 and 2

An example that was performed in the same way as Example 1-1 except thatthe ultraviolet rays of 2000 mJ/cm² were radiated in an atmosphericatmosphere in the process of radiating the ultraviolet rays was definedas Comparative Example 1. Further, an example that was performed in thesame way as Example 1-1 except that the ultraviolet rays were notradiated was defined as Comparative Example 2.

In each of Example 1 and Comparative Examples 1 and 2, an etching amountper unit time (an etching rate) was estimated by performing wet etchingwith dilute hydrofluoric acid of 0.5%. When the etching rate of thermaloxide films of silicon with respect to the dilute hydrofluoric acid of0.5% was defined as 1, relative etching rates in the respective exampleswere obtained.

The relative etching rates in Comparative Examples 1 and 2 were 3.74 and5.55, respectively. However, the relative etching rate in Example 1 was2.04.

According to this result, it may be considered that it is possible toincrease the etching strength by radiating the energy of the ultravioletrays to a coated film in a N₂ gas atmosphere before performing thecuring process when forming an insulating film by applying a coatingliquid containing polysilazane to a wafer W.

In addition, the amounts of atom bonds before and after the ultravioletray radiation treatment and after the curing treatment were estimatedusing a Fourier Transform Infrared spectrophotometer (FT-IR) in Example1 and Comparative Example 1. In Comparative Example 1, Si—H bondsdecreased and Si—O bond increased after the ultraviolet ray radiationtreatment. Further, in Example 1, Si—H bonds decreased but Si—O bondsdid not increase after the ultraviolet ray radiation treatment, and Si—Obonds increased after the curing treatment.

According to this result, it is presumed that since Si—H bonds weredecreased due to the ultraviolet ray radiation treatment, dangling bondscould be formed. However, it is presumed that, if the ultraviolet rayradiation treatment is performed in an atmospheric atmosphere,crosslinking reaction progresses before the curing treatment, and if theultraviolet ray radiation treatment is performed in a N₂ gas atmosphere,it is possible to suppress crosslinking reaction before the curingtreatment. Further, it is presumed that the etching strength isincreased by forming dangling bonds before the curing treatment andsuppressing crosslinking reaction.

Further, in examples in which processing was performed in the same wasas Example 1-1 except that the dosage of the ultraviolet rays was set as3000 and 4000 mJ/cm², similarly, the results of estimating relativeetching rates were 2.70 and 2.42, respectively. An insulating filmhaving high strength could be obtained at the dosage of about 4000mJ/cm² of the ultraviolet rays. As in Example 3 to be described below,in an example in which the dosage of the ultraviolet rays is set as 3000and 4000 mJ/cm², it is presumed that a layer that is a dense oxide filmis quickly formed in a surface, and the coated film after the curingtreatment is considered as a sufficiently dense film.

Example 2

Further, an insulating film was formed on a wafer W using the system forprocessing a substrate shown in FIG. 11 according to the followingexamples, and the etching strength of the insulating film was estimated,in order to examine the effect according to the heating temperature of awafer W in the solution volatilization process.

Example 2-1

The coating liquid described in the embodiment was applied to the waferW, the wafer W is heated at 150 degrees C. for 3 minutes in the solutionvolatilization process, and then the process of radiating theultraviolet rays was performed without performing the reflow process. Inthe subsequent curing process, the wafer W was heated through two stagesperformed at 400 degrees C. for 30 minutes and at 450 degrees C. for 120minutes with water vapor supplied in a heat treatment furnace, and thenthe wafer W was heated at 450 degrees C. in a N₂ gas atmosphere. Thetarget thickness of a coated film was 100 nm.

Examples 2-2 and 2-3

Examples in which processing was performed in the same way as Example2-1 except that the heating temperature of a wafer W in the solutionvolatilization process was set as 200 degrees C. and 250 degrees C.,respectively, were defined as Examples 2-2 and 2-3, respectively.

The relative etching rates in Examples 2-1, 2-2, and 2-3 were 3.68,2.74, and 2.74, respectively. It may be considered that a denser andbetter insulting film can be obtained by increasing the heatingtemperature of a wafer W in the solution volatilization process.

Example 3

The following tests were performed to examine suppression of oxidationof a coated film due to forming a dense oxide film on the surface of thecoated film.

Example 3-1-1

A polysilazane film was formed on the surface of a wafer W using thesystem for processing a substrate shown in FIG. 11 , and then the waferW was heated at 150 degrees C. for 30 minutes. Next, the ultravioletrays having an intensity of 40 mW/cm² were radiated to the wafer in anitrogen gas atmosphere to obtain a dosage of 1000 mJ/cm². Next, thewafer W was accommodated in a carrier C. and was left for 1 day in anatmospheric atmosphere at a room temperature (25 degrees C.).Subsequently, the wafer W was transferred to a heat treatment apparatus,and then heated at 400 degrees C. for 3 minutes and at 450 degrees C.for 120 minutes in a water vapor atmosphere as the curing treatment.This example is defined as Example 3-1-1. Further, the target thicknessof a coated film was 120 nm.

Examples 3-1-2 and 3-1-3

Examples in which processing was performed in the same way as Example3-1-1 except that the dosages of the ultraviolet rays were 2000 mJ/cm²and 3000 mJ/cm² were defined as Examples 3-1-2 and 3-1-3, respectively.

Example 3-2-1

An example in which processing was performed in the same way as Example3-1-1 except that a wafer W was heated at 400 degrees C. for 3 minutesand at 600 degrees C. for 120 minutes in a water vapor atmosphere as thecuring treatment was defined as Example 3-2-1.

Examples 3-2-2 to 3-2-4

Examples in which processing was performed in the same way as Example3-2-1 except that the dosages of the ultraviolet rays radiated to coatedfilms were 2000 mJ/cm², 3000 mJ/cm², and 4000 mJ/cm² were defined asExamples 3-2-2 to 3-2-4, respectively.

Comparative Examples 3-1 and 3-2

Examples in which processing was performed in the same way as Examples3-1-1 and 3-2-1 except that the ultraviolet rays were not radiated tocoated films were defined as Comparative Examples 3-1 and 3-2,respectively.

In Examples 3-1-1 to 3-2-4 Comparative Examples 3-1 and 3-2, etchingrates with respect to a solution of dilute hydrofluoric acid of 0.5%were obtained, and relative etching rates to an etching rate of asilicon oxide film manufactured by thermal oxidation treatment withrespect to the solution of dilute hydrofluoric acid of 0.5% wereobtained.

FIG. 27 shows the result and is a characteristic diagram showingrelative etching rates in Examples 3-1-1 to 3-2-4 and ComparativeExamples 3-1 and 3-2. As shown in FIG. 27 , the relative etching rateswere 4.12 and 3.05 in Comparative Examples 3-1 and 3-2, respectively.However, in any cases of Examples 3-1-1 to 3-1-3 and Examples 3-2-1 to3-2-4, the relative etching rates were low in accordance with anincrease in dosage of the ultraviolet rays.

The relative etching rate dropped to near 1 in Example 3-2-4 in whichthe temperature in the curing treatment was set to 600 degrees C. Therelative etching rate dropped up to about 2 even in Example 3-1-3 inwhich the temperature in the curing treatment was set to 450 degrees C.Accordingly, it is possible to obtain an insulating film having higheretching strength by increasing the dosage of the ultraviolet rays in theprocessing of radiating the ultraviolet rays to a coated film. Further,it is possible to obtain an insulating film with sufficiently highetching strength when the temperature in the curing treatment is loweven though the wafer W is left for a period.

What is claimed is:
 1. An apparatus for processing a substrate,comprising: a coating module configured to form a coated film on asubstrate by applying a first coating liquid, which is obtained bydissolving a precursor for forming an insulating film containing siliconoxide in a solvent, to the substrate; a solvent volatilization moduleconfigured to volatilize the solvent in the coated film; an energysupply module configured to supply energy to the coated film in whichthe solvent has been volatilized, in a low-oxygen atmosphere having aconcentration of oxygen lower than an atmospheric atmosphere so as toactivate the precursor; a protective film formation module configured tosupply a second coating liquid on the coated film to which the energyhas been supplied by the energy supply module to form a protective filmformed of the second coating liquid on the coated film; a substratetransfer mechanism configured to transfer the substrate between thecoating module, the solvent volatilization module, the energy supplymodule, and the protective film formation module; and a controllerconfigured to execute a process including: after the energy is suppliedby the energy supply module to the coated film in which the solvent hasbeen volatilized, supplying, by the protective film formation module,the second coating liquid on the coated film to which the energy hasbeen supplied.
 2. The apparatus of claim 1, wherein the protective filmformation module is an organic film formation module configured tosupply the second coating liquid so as to form an organic film formed ofthe second coating liquid on a surface of the coated film.
 3. Theapparatus of claim 1, wherein the protective film formation module isintegral with the energy supply module, and the energy supply moduleforms dangling bonds at molecular groups constituting the precursor andforms a layer, which has a high activity and is a dense oxide layer, byoxidation, on a surface of the coated film.
 4. The apparatus of claim 1,wherein the solvent volatilization module is a solution-heating moduleconfigured to heat the substrate.
 5. The apparatus of claim 1, furthercomprising: a reflow-heating module configured to heat the substrate torearrange molecular groups in the coated film in which the solvent hasbeen volatilized.
 6. The apparatus of claim 1, wherein the energy supplymodule is a module configured to radiate ultraviolet rays of which amain wavelength is shorter than 200 nm, to the coated film.
 7. A systemfor processing a substrate, comprising: an apparatus for processing asubstrate which includes: a load/unload port configured to load/unloadthe substrate accommodated in a transfer container; a coating moduleconfigured to form a coated film on the substrate by applying a firstcoating liquid, which is obtained by dissolving a precursor for formingan insulating film containing silicon oxide in a solvent, to thesubstrate; a solvent volatilization module configured to volatilize thesolvent in the coated film; an energy supply module configured to supplyenergy to the coated film in which the solvent has been volatilized, ina low-oxygen atmosphere having a concentration of oxygen lower than anatmospheric atmosphere so as to activate the precursor; a protectivefilm formation module configured to supply a second coating liquid onthe coated film to which the energy has been supplied by the energysupply module to form a protective film formed of the second coatingliquid on the coated film; a substrate transfer mechanism configured totransfer the substrate between the coating module, the solventvolatilization module, the energy supply module, the protective filmformation module, and the load/unload port; and a controller configuredto execute a process including: after the energy is supplied by theenergy supply module to the coated film in which the solvent has beenvolatilized, supplying, by the protective film formation module, thesecond coating liquid on the coated film to which the energy has beensupplied; a heat treatment apparatus configured to form the insulatingfilm by heating the substrate processed in the apparatus for processingthe substrate and crosslinking the precursor; and a container transfermechanism configured to transfer the transfer container between theload/unload port of the apparatus for processing the substrate and theheat treatment apparatus.